An oxidation reaction is a most basic reaction in the field of industrial organic chemistry, and there are a variety of known oxidation processes, in particular an oxidation process for a substrate using nitric acid. By way of illustration, adipic acid that is a raw material for the production of nylon 66 is prepared by a process of oxidizing cyclohexanol and no other, or a mixture of cyclohexanol and cyclohexane (KA oil) with nitric acid. A long-chain dicarboxylic acid (e.g., suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid) is produced by a process of oxidizing a corresponding macrocyclic (large-ring) cycloalkane (e.g., cyclooctane, cyclononane, cyclodecane, cyclododecane) with the use of nitric acid, and such a long-chain dicarboxylic acid is employed as a raw material for the production of polyesters or polyamides.
Each of these processes, however, requires an expensive exhaust gas treatment plant for treatment of N.sub.2 O and NO.sub.x produced by the oxidation with nitric acid.
In view of these problems, production processes for adipic acid by oxidative carbonylation of butadiene or carbon monoxide (CO) insertion technology have been investigated. These technologies, however, are insufficient for commercial production.
A preferred oxidation process from the viewpoints of resources and environment is a catalytic oxidation, which is conducted with direct use of molecular oxygen or air as an oxidizing agent. Therefore, there has been investigated an oxidation process, which comprises contacting a substrate catalytically and directly with molecular oxygen in the presence of a cobalt catalyst or a boric acid catalyst. By way of example, an oxidation process has been examined, which comprises direct and catalytic contact of cyclohexane, a macrocyclic cycloalkane, or other cycloalkanes or cycloalkenes with molecular oxygen in the presence of a cobalt catalyst or a boric acid catalyst. The use of the cobalt catalyst in the catalytic system, however, requires recovery of the expensive cobalt catalyst, or results in precipitation of the cobalt catalyst. Further, such a catalytic oxidation requires a high temperature and/or a high pressure for activation of oxygen, and the process has still insufficient transformation rate and selectivity. Moreover, to retain the selectivity in a high level, the production process of adipic acid requires to form adipic acid with suppressing the transformation rate or conversion at about 10%. Therefore, according to the catalytic oxidation, commercially satisfactory conversion and selectivity would not be expected in the production of an oxide (e.g., adipic acid, cyclohexenol, cyclohexene) from a corresponding substrate (e.g., cyclohexane or other cycloalkanes, cycloalkenes) under mild conditions.
As for oxidation of a macrocyclic cycloalkane, Japanese Patent Publication No. 3100/1968 (JP-B-43-3100) discloses a production process of lactam, which is used as a raw material for the production of nylon 12. This process comprises the steps of oxidizing cyclododecane with air in the presence of a boric acid catalyst, dehydrogenating cyclododecanol of the products to give cyclododecanone, and reacting cyclododecanone with nitrosylsulfuric acid by Beckmann's rearrangement. However, the macrocyclic cycloalkane is stabler and less reactive than cyclohexane. Accordingly, the conversion of cyclododecane is so small, in the above oxidation process using air, that a yield of cyclododecanone is still insufficient even inclusive of cyclododecanol. In particular, according to the catalytic oxidation commercial production of an oxide (e.g., a carbonyl compound or a carboxylic acid) would not be expected with high yield and high efficiency from a corresponding macrocyclic cycloalkane under mild or moderate conditions.
Incidentally, an attempt has been made for oxidation of a substrate using a radical initiator such as azobisisobutyronitrile in the presence of oxygen, as well. According to this technology, however, it is difficult to produce an oxidized compound from a corresponding cycloalkene with high selectivity and a good yield.
On the other hand, a polycyclic hydrocarbon having a carbon-hydrogen bond (methylidyne group) in a fusing or junction site of adjacent rings or in a bridgehead position can be prepared by hydrogenation and thermal conversion (thermal transfer) of a polycyclic aromatic compound (e.g., naphthalene, acenaphthene, anthracene, phenanthrene, phenalene, or alkyl-substituted derivatives of these compounds) at a high temperature under a high pressure Japanese Patent Publication No. 2909/1977 (JP-B-52-2909), Japanese Patent Publication No. 12706/1977 (JP-B-52-12706), Japanese Patent Publication No. 35942/1978 (JP-B-53-35942), Japanese Patent Publication No. 35944/1978 (JP-B-53-35944), Japanese Patent Application Laid-open No. 246333/1985 (JP-A-60-246333)!. Such a polycyclic aromatic compound is available abundantly in purification process of petroleum. The polycyclic hydrocarbon as prepared in such a technology is thermally stable and thus employed as a higher lubricating oil, which requires heat resisting property.
The polycyclic hydrocarbons respectively have skeletons, which insure mutual stabilization of each ring, such as adamantane and other compounds having a three-dimensionally symmetric structure, and, as a result, endowed with distinctive functions. Thus, various copolymers each having enhanced or improved function or characteristics can be obtained by introducing a hydroxyl group into such polycyclic hydrocarbons and, if necessary, inducing them into an acrylic acid derivative or a carbonate. In a bridged cyclic hydrocarbon having a methine-carbon atom in a bridgehead position, there have been proposed various production processes for obtaining such copolymers from a functional group-introduced adamantane. The processes include, for example, a process of producing a polyester Japanese Patent Publication No. 26792/1967 (JP-B-42-26792), Japanese Patent Publication No. 937/1968 (JP-B-43-937), Japanese Patent Publication No. 34628/1971 (JP-B-46-34628), Japanese Patent Application Laid-open No. 21090/1975 (JP-A-50-21090)!, a process of producing a polycarbonate U.S. Pat. No. 3,516,969, U.S. Pat. No. 3,594,427!, a process for producing a polyamide or a polyimide Japanese Patent Publication No. 2024/1970 (JP-B-45-2024), U.S. Pat. No. 3,832,332, U.S. Pat. No. 3,814,735!, a process for producing a polyurethane Japanese Patent Publication No. 700/1968 (JP-B-43-700), Japanese Patent Publication No. 6456/1968 (JP-B-43-6456), Japanese Patent Publication No. 6267/1969 (JP-B-44-6267), Japanese Patent Publication No. 12891/1969 (JP-B-44-12891)!, a process for producing a polysulfone and a polysulfonate U.S. Pat. No. 3,738,960, U.S. Pat. No. 3,738,965, U.S. Pat. No. 3,753,950!, and a process for producing a vinyl polymer Japanese Patent Publication No. 36950/1970 (JP-B-45-36950), Japanese Patent Publication No. 28419/1971 (JP-B-46-28419)!. Further, a homopolymer as produced using a polycyclic hydrocarbon as a monomer has also been proposed (U.S. Pat. No. 3,649,702).
Polymers each containing such a polycyclic hydrocarbon have generally excellent functions or characteristics (high functionality). They have, for example, excellent heat resistance (heat resisting property), moisture resistance, small light-inducing loss, high refractive index, double refraction index and other optical characteristics, coefficient of thermal expansion and other characteristics. Such excellent characteristics cannot be achieved with the use of conventional polymers. Accordingly, their applications have been investigated for optical fibers, optical elements, optical lenses, hologram, optical discs, contact lenses and other optical materials, transparent resin coating compositions for organic glasses, electric conductive polymers, photosensitive materials, fluorescent materials and so forth.
Incidentally, an amino derivative derived from an alcohol of a bridged cyclic hydrocarbon is useful for introducing various pharmaceuticals and/or agricultural chemicals each having excellent pharmacological activity, such as "SYMMETREL" (a trade name) as a therapeutic agent for Parkinson's disease, typically speaking. By way of example, adamantane, hemiadamantane, norbornene, tetralin and their derivatives are used for such applications.
As described above, polycyclic hydrocarbons each having a functional group in a bridgehead position are compounds applicable to many applications, and most of these compounds may be induced or derived from corresponding alcohols. In particular, polyols each substituted with hydroxyl groups on plural, i.e., two or more bridgehead positions can be advantageously employed for production of progressive materials (highly functional materials). However, it is difficult to introduce hydroxyl groups into the bridgehead positions of such chemically stable polycyclic hydrocarbons with effectiveness and high efficiency. By way of illustration, introduction of hydroxyl groups is conducted by bromination of a bridged cyclic hydrocarbon (e.g., adamantane or its derivative) with the use of excess bromine (e.g., 10 times by mole or more), and hydrolyzing the formed bromide with silver nitrate or silver sulfate in an excess amount greater than a stoichiometric amount (Chem. Ber., 92, 1629 (1959), 93, 226, 1161 (1960): J. Org. Chem., 26 2207 (1961)).
In this process, however, the reaction should be conducted over a long period at a temperature of about 100.degree. C. using a large quantity of bromine. Besides, the reaction consumes the expensive silver reagent in a large quantity. Moreover, successive bromination of two or more bridgehead positions would not be expected. Therefore, a catalyst such as boron tribromide and aluminum tribromide is required when adamantane is employed in the process. In the bromination process, loss in the hydrolysis step is so great that the recoveries of an adamantanemonool and an adamantanediol are at most 81% and 57%, respectively, in terms of the produced alcohols. In addition, since an adamantanetriol cannot be formed directly from adamantane, it has to be produced by isolation and hydrolysis of a successively highly brominated compound. Accordingly, the yield of the adamantanetriol is extremely low at about 10 to 30% Tetrahedron Letters, 19 1841 (1967); Just. Liebigs Ann. Chem., 717 60 (1968)!.
As a process for producing an adamantanediol, there has been known an oxidation process using chromic acid as well. For example, Japanese Patent Publication No. 16621/1967 (JP-B-42-16621) discloses that an adamantanediol is obtained in a yield of 96% and selectivity of 96% by reacting adamantane with five times by mole or more of chromic acid in a concentrated acetic acid solution at a temperature of 90.degree. C. This technology is useful for oxidation of a bridgehead of a polycyclic hydrocarbon to form an alcohol derivative. However, this technology requires an excessive amount of expensive chromic acid. Such a reagent is highly toxic, and in addition, an after-treatment and/or recovery equipment is required. Therefore, the process is disadvantageous in commercial production. Moreover, an excess amount of sulfuric acid is necessary in addition to chromic acid. Furthermore, it is necessary to control the reaction temperature and the concentration of acetic acid as a solvent, so that the process would not have excellent reaction workability. Further, although an adamantanediol is formed according to the process, oxidation of adamantane to a triol or higher polyol will not proceed, even when the reaction is carried out in severe conditions.
Regarding a catalytic oxidation in which molecular oxygen or air is directly used as an oxidizing agent, Japanese Patent Publication No. 26792/1967 (JP-B-42-26792) describes, for instance, a process that comprises heating adamantane at oxygen pressure of 7 kg/cm.sup.2 at 170.degree. C. in the presence of a catalytic amount of cobalt naphthenate and without a solvent, and ceasing the reaction when a transformation rate of adamantane reaches 70%. The reaction mixture obtained in such a process comprises an adamantanemonool oxidized in a bridgehead position in a yield of 41%, but it contains an adamantanediol merely in a trace amount. Still more, when the heating is continued until the transformation rate of adamantane reaches 99%, the reaction not only provides adamantanediols in a yield of 25% but also by-produces a large quantity of ketone derivatives formed as a result of isomerization and oxidation. Therefore, the intended compound can hardly be isolated and purified from the reaction products.
As thus described, it is difficult to produce a polyol such as a diol, in particular triol, tetraol, or a higher polyol with high effectiveness and efficiency inhibiting production of a ketone in the production of a polycyclic hydrocarbon such as adamantane. In particular, it is difficult to prepare the polyol in mild conditions with a high transformation rate and excellent selectivity. Meanwhile, such a polycyclic hydrocarbon is useful for impartment of excellent functions.
Japanese Patent Application Laid-open No. 310610/1993 (JP-A-5-310610) discloses the results of investigations with respect to other metal species than the cobalt as a catalyst for oxidation with air. The catalysts described in the literature, however, have insufficient catalytic activities, and hence it is difficult to obtain an oxidized compound from a corresponding polycyclic hydrocarbon with high selectivity and an excellent yield.
Incidentally, the compounds, which are substituted with a hydroxyl group on a tertiary carbon atom of a junction site where adjacent rings bond each other, are useful as physiologically active substances. They have excellent utilizing values as antivirus agents, antibacterial or antifungal agents, plant hormones or the like. Further, compounds having a functional group bonded to a carbon atom of a junction position of rings are widely employed as raw materials for the production of various perfumes and fragrant compounds. Therefore, such tertiary alcohols each having a hydroxyl group in a junction position of rings are important compounds. However, when a compound having a methylidyne group in a junction site of adjacent rings is oxidized, the junction position of the adjacent rings oxidatively cleaves to form a corresponding diketone as a main product. Accordingly, it is difficult to introduce a hydroxyl group into the junction position of the rings and inhibit the formation of diketones at the same time. Consequently, a special technology with the use of substrate-specificity is employed to obtain tertiary alcohols.
By way of illustration, Japanese Patent Publication No. 5894/1987 (JP-B-62-5894) discloses a process for producing hexahydroindanol having a tertiary hydroxyl group by ring-opening epoxytetrahydroindane. The epoxytetrahydroindane has been produced by epoxidation of tetrahydroindane with the use of an aluminum alkoxide catalyst. Such hexahydroindanol and its derivatives give out fragrance or aroma, for example, like a leaf, green, camphor, ligneous, patchouli, musk, root, vervet, American carrot, pine root, soil and the like. Therefore, these compounds are used as fragrance or perfumes for various materials for the production of cologne, foods, tobacco products and so on. However, the production of the hexahydroindanol requires partial hydrogenation step of indene to give tetrahydroindane and an epoxidation step of the produced tetrahydroindane. Further, the selectivity in each reaction step is so low that the yield of an object compound is extremely small as a whole inclusive of a ring-opening step of the epoxy compound. Therefore, use of indene, as a raw material, which is available at a comparatively low cost, still fails to provide an object compound with economic advantages.
Japanese Patent Publication No. 42972/1980 (JP-B-55-42972) discloses the production of 1-hydroxytricyclo4.3.1.1.sup.2,5 !undecane by hydrolysis of 1-halogenotricyclo4.3.1.1.sup.2,5 !undecane. The 1-hydroxytricyclo4.3.1.1.sup.2,5 !undecane is employed as a raw material for the production of a pharmacologically active compound, such as an amino compound having strong anti-virus activity. In Japanese Patent Application Laid-open No. 13760/1976 (JP-A-51-13760), 1-halogenotricyclo4.3.1.1.sup.2,5 !undecane is prepared by bromination of tricyclo4.3.1.1.sup.2,5 !undecane. The yield of the bromide is, however, only about 65%, and the yield of the amino compound inclusive of an amination step is lower than 60%. Further, since a corresponding chloride cannot be induced directly from tricyclo4.3.1.1.sup.2,5 !undecane, it 2 is formed by reacting 1-hydroxytricyclo4.3.1.1.sup.2,5 !undecane with an acyl chloride. As described above, tricyclo4.3.1.1.sup.2,5 !undecane has a plenty of positions that can be oxidized, i.e., two junction sites in which the adjacent rings bond each other, two bridgehead positions, and seven methylene positions. Accordingly, direct introduction of a hydroxyl group would not be expected with high selectivity according to a conventional oxidation technology such as oxidation with chromic acid or oxidation with air.
Japanese Patent Publication No. 114538/1982 (JP-B-57-114538) discloses the preparation of 2-endohydroxy-exotricyclo5.2.1.0.sup.2,6 !decane by treating exotricyclo5.2.1.0.sup.2,6 !decane with an organic peroxide. This alcohol is a fragrant substance having a strong aroma or fragrance like woody camphor, and is a physiologically active substance having antivirus activity, antifungal or antimicrobial activity and plant hormone activity. Such characteristics are also found in 2-hydroxyendotricyclo5.2.2.0.sup.2,6 !undecane as produced by treating endotricyclo5.2.2.0.sup.2.6 !undecane with an organic peroxide Japanese Patent Publication No. 114539/1982 (JP-B-57-114539)!. However, according to the oxidation with a peroxide, the yield of the object compound is so low at about 20 to 50%. Incidentally, the endotricyclo5.2.2.0.sup.2,6 !undecane can easily be obtained as a derivative of dicyclopentadiene Japanese Patent Publication No. 36748/1976 (JP-B-51-36748); Synth. Comm., 4, 225 (1974)!.
As described above, it is also difficult to introduce a hydroxyl group easily and effectively into a tertiary carbon atom in the junction site, where adjacent rings bond or fuse each other, in a polycyclic hydrocarbon, while inhibiting ring-opening and by-production of a diketone.
Further, an aromatic compound having a carboxyl group (e.g., benzoic acid) has been produced by a process that comprises oxidizing an aromatic compound having a methyl group (e.g., toluene) with nitric acid or dichromic acid. Such a process is useful for production of an aromatic compound having a carboxyl group, such as benzoic acid, with a comparatively high yield. The oxidation process with nitric acid, however, requires expensive equipment for treating exhaust gas, i.e., produced N.sub.2 O and NO.sub.x. Similarly, the oxidation process with dichromic acid requires treatment of a chromium component.
Regarding production processes of benzoic acid using oxidation with air, there have been known a process that comprises oxidizing toluene in a liquid phase with the use of cobalt naphthenate. A process that comprises oxidizing toluene in a liquid phase in the presence of a catalytic system containing cobalt-manganese acetate and a bromide is also known. However, the process using cobalt naphthenate has insufficient transformation rate and selectivity, so that efficient production of benzoic acid would not be expected. On the other hand, the process using cobalt-manganese acetate provides benzoic acid with a comparatively high yield. The reaction according to this technology, however, needs to be conducted at a comparatively high temperature (for example, about 150 to 250.degree. C.). Therefore, it is difficult to efficiently produce a carboxylic acid from a corresponding aromatic hydrocarbon having a methyl group, inclusive of toluene, by means of oxidation with oxygen in mild or moderate conditions.
Terephthalic acid can be prepared at a comparatively low temperature (e.g., about 90 to 160.degree. C.) by oxidizing other aromatic compound such as p-xylene with air in the presence of cobalt acetate and a co-oxidizing agent. In this process, however, not only the catalyst should be circulated in a large quantity, but also acetic acid is by-produced in an equimole amount with terephthalic acid.
Butenediol has been employed as a raw material (starting material) for the production of polyamide and other synthetic resins, maleic anhydride, and plasticizers. Further, butanediol introduced from butenediol is useful, for example, as a raw material for the production of tetrahydrofuran, butyrolactone, polyester or polyurethane. The butenediol or butanediol can be obtained by preparing butynediol with the use of Reppe reaction and hydrogenating the produced butynediol using a reduction catalyst.
On the other hand, conjugate diene such as butadiene is produced in a large quantity in petroleum purification steps. Accordingly, it is commercially useful to directly produce an alkenediol such as butenediol from a corresponding conjugate diene such as butadiene. As for a production process of a diol from a conjugate diene, it is possible to oxidize a conjugate diene with nitric acid to give a corresponding diol. As described above, however, the technology requires expensive equipment for the treatment of N.sub.2 O and NO.sub.x as formed by oxidation with nitric acid. Therefore, such a process is more useful from the viewpoints of resource and environment that provides an alkenediol efficiently by a catalytic oxidation technology directly using molecular oxygen or air as an oxidizing agent. Further, this oxidation technology using oxygen or air as an oxidizing agent would be greatly useful if such an oxidation process is effective in oxidation of other conjugate compounds than the conjugate diene, e.g., oxidation of an .alpha.,.beta.-unsaturated bond of acrylic acid or its derivative to give a corresponding oxide efficiently.
However, according to oxidation with oxygen, in particular oxidation with oxygen in mild condition, it is difficult to produce a diol or its derivative (e.g., an alkenediol, acetal) from a corresponding conjugate diene, acrylic acid or its derivative, or other conjugate compounds with high selectivity and an excellent yield.
In page 762 of the "Lecture Draft II" (1994) of 67th Spring Annual Meeting of Chemical Society of Japan, it is reported that oxidation of an alcohol such as benzyl alcohol or benzhydrol with air using vanadomolybdophosphoriate and N-hydroxyphthalimide provides a ketone such as acetophenone or benzophenone in a high yield, and that oxidation of tetralin, isochroman or adamantane with oxygen using N-hydroxyphthalimide gives a corresponding monoalcohol or monoketone.
It is, therefore, an object of the present invention to provide an oxidation catalyst which insures efficient oxidation of a substrate by means of oxidation with oxygen, and which does not particularly require treatment of exhaust gas, and an oxidation process using this catalyst.
It is another object of the invention to provide an oxidation catalyst that provides an oxide (e.g., ketone, alcohol, aldehyde, a carboxylic acid) with a high transformation rate or conversion and selectivity from a corresponding substrate (e.g., cycloalkane, cycloalkene, polycyclic hydrocarbon, an alkyl group-substituted aromatic compound, a conjugate compound) by means of oxidation with molecular oxygen, an oxidation process using this catalyst, and a production process of the oxide.
A further object of the invention is to provide an oxidation catalyst, which insures direct and efficient production, with high transformation rate and selectivity, of a carboxylic acid (e.g., adipic acid or other long-chain dicarboxylic acids, and aromatic carboxylic acids) or a ketone (e.g., cycloalkane, cycloalkenone, aromatic ketone) from a corresponding substrate (e.g., a cycloalkane, a cycloalkene, an alkyl-substituted aromatic compound) by means of contact with oxygen in mild or moderate conditions, an oxidation process with the use of this catalyst, and a production process of the carboxylic acid or ketone.
It is yet another object of the invention to provide an oxidation catalyst, which provides efficient oxidation with oxygen of a methylidyne group in a bridgehead position or junction position of a polycyclic hydrocarbon, and an oxidation process using this catalyst.
A further object of the invention is to provide an oxidation catalyst that provides a diol or higher polyol from a corresponding condensed polycyclic hydrocarbon or a bridged (cross-linked) cyclic hydrocarbon with high transformation rate and selectivity, and an oxidation process using this catalyst.
It is still another object of the invention to provide an oxidation catalyst and an oxidation process, both of which insure efficient introduction of a hydroxyl group into a tertiary carbon atom of the junction position of a polycyclic hydrocarbon in mild conditions while suppressing cleavage of the ring of the polycyclic hydrocarbon and by-production of a diketone.
A still further object of the invention is to provide a process for producing an adamantanepolyol, which provides, with effectiveness and a high yield, an adamantanediol, adamantanetriol or higher adamantanepolyol by means of oxidation with oxygen in mild conditions.